creighton



E. E. F. CREEGHTON. FRQFECHON 0F TRANSMISSION SYSTEMS.

APPucmms man APR. I916.

[313,072. -Paten tedAug.12,1919. g 2 SHEETSSHEET l.

Fig. 2.

Inventor H'ime'rfFCrei hton, b

His Attorney;

E E. F. CREIGHTON. PROTECTION OF TRANSM|SSION SYSTEMS.

APPLICATION FILED APR. 7. I916 Patented Au"; 1

2 SHEETS HkEI 2.

Inventor- Elmer hton,

ELFTChei His ttohne f' UNITED STATES PATENT] oFn oE.

ELMER E. F. c EIGHToN, or SCHENECTADY, NEW YoaK. ASSIGNOR .To German.

ELECTRIC COMPANY, A CORPORATION or NEW YORK. I

PROTECTION OF TRANSMISSION SYSTEMS.

Specification of Letters Patent.

Patented Aug. 12, 1919.

I '0 all whom it may concern:

Be it known that I, Emma E. F. CREIGH- 'rox, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in the Protection of Transmission Systems, of which the fol lowing is a s cification.

My invention relates to the protection of transmission systems and more particularly to means for disconnecting a feeder upon which a fault has occurred and for selec-.

.tively, indicating the phase of the feeder at fault.

The object of my invention is to provide a novel ,nndin' proved means ofiprotection for a systemzof distributionuponthe occiirrcnce thereon of a fault and especially to protect a system of distribution upon the occurrence thereon of a broken .line wire or an open. circuit.

My novel means of protection comprises,

in general a phase selectiverelay operative in response to an unbalam-hnc, of'the load or power conditions between phases on a feeder, this relay operating with a differentialaction to select the phase of the feeder at fault. Thisrelay ivillprotecta system from nearly every condition of broken line wire but to meet afew conditions that iiiayexis't upon which my phase selective/relay may not be operative. I prefer to\ usefin (.Qll'lblllll' tion with my phase selective relay, another unbalancing between any phase and ground.

' 'ith these two types of relays. I am able. to'

when a break in a line 'wirefor an open cir.-.

cult occu1's, by disconnecting the faulty feeder from the system, notifying the operator'of the o ')ening-of-the feederjclrcuitandj selectivelyindicating the faultyv phase of the faulty feeder. The type of phaseselectiverelay or load oi power responsive device which I have developed to respon d to dfiblllancingoftheloa'd or-power conditions between phases is applicable to both nongrounded a'ndgroundedsystems-but the re-'* lay which I use responsive to unlmlam'in;

T between the system andground is ot' a; different construction depemlent upon whether the-system to be protected operated with a grounded or non-grtmnded neutral.

Thenovel fcatureswhich libelievelto be to the. following description taken in connection with the accompanying drawings in which Figure 1 shows diagrammatically, the ap plication of my phase selective relay con nected to a single feeder of a system of distribution. Fig. 2 is a diagrammatic view of the connections of this relay to the line tp lie-protected. F g. 3 1s a. more detailed viewof the relay itself. Fig. 4 is .a diarammatic view of a system comprising a plurality of feeders embodying the principles of my invention. Fig. 5 shows my invention applied to the protection of a single feeder of a'system of dlstribut-lon having a grounded neutral, and Fig. 6 shows my invention applied to the protection of'a single feeder ofa non-grounded system.

It will be apparent that when a line wire breaks on a transn'nssion line, a great number of. different conditions may exist which vary depending on whether the system has a grounded or non-grounded neutral, whether-current or power can be fed from both ends of the system or only from one end. The conditions existing on the system also depend in each of these instances. upon the character of the break. that is. whether -[the break. is such hat neithercnd of the. line relay which is operative in response to an wire: touches thc ground. that is. an open cireuit; whether onlyone end of the line .90

\'ire touches the ground; or whether both ends of the l ne wire touch the ground.

Each of these conditions also vary according to whether the break occurs near the power station or out on the line and whether,

the wire or wires .groundedform high, nit dium orlow resistance paths.

'Broken line wires cause very detrimental conditions to exist on transmission lines.

l n'der some. conditions pol'yphase apparatus will he operated single phase or may be destroyed due to overheating, while under other conditions a broken line wire may exist without boin; known at the central station.

7 1 l nder all conditions a broken line \VIIQ. IS a great menace to life and it therefore, imperative that such a condition on a systeirp should be remedied as quickly as possible.

In Fig. l is shown a feeder 1, 2,.of a 'polyphase transmission line connected 1351 tween two stations A and B. To protect this feeder upon the occurrence 'ofa broken llne wire, I connect at both ends of the feeder, at stations A and B, one of my phase selective or load responsive relays, which I have shown diagrammatically, as comprising three Wattmeter elements 4, 5, 6 and 7, 8, 9 respectively, one element of each relay being connected to-eac-h phase. The wattmeter element's comprising-my phase selective relay are arranged to operate differentially in response to load or power unbal ancing between the phases of the feeder,

Asis well understood, a wattm'eter element depends fOr.,it8 "8Ct1Qn on theproduct of cunent,"potential';and the cosine of the angle fij'where Q the angle of phase;displacement betweenthe current and poten-. tial, that is,- the torque or pull ofa watt meter element is}, a. function of orjprpportional tease product-of currenfi flotential and powerfactor; Ifany one'ofi ese fac-' A torsifallsgkto ractically zerb, it: isevident tors to fall-to zeroffiependingon' the'char-. of, .the 'brealband fthenature of 1 the system and r-depend these principles to obtain a selective action oli my wattmeter,

tors is then zero.-

that the-wawneterelement: has practically no. t'orque or pullas the product of the facoccurrence of, a broken line Wire may any of these fac element relay.

For the application of my selective relay to the protection of a system of distribution,

l' have shown in Fig. 1 one feeder connected between two stations, A and B, it being 7 understood that-such feeder may be one of several inparallel or one of several radial feeders, such as shown in Fig. 5, or may be one between tw stations on a system having. several statidns-in series in which case aselective 'r elay. is connected on both sides of the stations. p To more clearly, show the connection of the wattmeter elements of my selective relay to the feederto be protected I haveidiaigrammatically shown in Fig. 2, the connections of'my relay atstation A comprising wattmeter elements 4, 5 and 6 it being'understood that my relay comprising wattmeter elements 7,18 and!) are similarly connected .at. station. B. Each. of the wattmeter elements 4, 5 and (i-consist of current coils 1Q, 11,-and 12 and potential coils 13, 1'4 and 1?),

respectively, eaclncurrent coil receiving cur rent: from its respective phase'through the secondaries. of current transformers i6, 17

and 18 and each potential coil receiving the potential of its respective phase through the secondaries of potential transformcrsh), 20

and 21.. VVattmeter elements 4, 5 and 6, therefore, receive current and potential from their correspondingphase 1. 2 and 3, re-

. specti vcly.

I order to obtain a differential action of member 22 are therefore movable in re sponse to the wattmeter elements 4, 5 and 6, respectively. Under normal condition the pulls exerted on each arm by their respective wattmeter elements are equal and hence the member or armature 22 is held electrically baldnced. Should, however, the pull exerted on one arm, 23'for instance, by its wattmeter element 4 become weakened due to a reduction in one of the factors, current, potential or power factor on phase 1, the pull exerted on the other arms 24 and 25 by. their wattmeter elements 5 and 6 respectively, move the member 22' so that arms 24 and 25 are moved down consequently raising arm 23.

To {give an indication of the operation of my re ay and to render it operative to select the phase atfault, I provide above each of the arins 23, 24 and 25, fixed contacts 26, 27

and 28, respectively which I have shown as preferably resiliently mounted on support- .ing members 29. When the relay is operated as has just been described, to move one of the arms 23, 24 or 25 upwardly, this arm closes a circuit from a source of excitation such as a battery 30, along arms 23, 24 or 25, through the contacts 26, 27 or 28, phase indicating ,or-recording devices 31, 3201' 33, thence by conductors 34, 35,- or 36 toa commo'h alarm device or indicator 37 and then through a common auxiliary relay or solenoidi88 back to the battery 30. I have shown phase recording device 31 diagrammatically, as a drop indicator, it being understood that devices 32 and 33 are similar.

and that these devices may be a'nnunciabors or like devices capable of'maintaining an indication of the passage of an electric current. It is thusapparent that if 'the'pull, for instance, of wattmeter element 4 is weakened corresponding to a faulty condition on phase 1, as previously stated, that its arm 23 is raised to'engage its contact 26 and complete the=circuit just described, causing the operation of its phase recorder 31. the alarm device 37 and the relay 38. The operation of alarm 37 gives the operator an indication of the operation of the relay. \vh'ile relay 38 on becoming energized doses its contacts to omplcte the circuit of trip coil39, as shown in Fig. .5, and thereby cause the-opening of oil switch 40.. As soon as the oil switch opens, the phase selective balanced condition. By observing, however,

the phase recorders 31, 32 and '33 the phase 10, 11 and 12 respectively of the wattn'ieter relay. Inorder to obtain a pull on the rod 49 which is proportional to the load on the feeder to be protected, I reverse one otthe which isfat fault canbe'readily determined windings 50,51 or 52 in relation to the 70 and the recorder returned to normal posiother two, either by a reversed connection tion. such as shown in Fig. 5 for winding 52 or In order to provide'further selective acby a reversed winding. I thus provide a tion of, my phase selective relay,under conmeans for automatically positioning memditions to be later described, I provide my ber 17 proportional to the load and thereby 75 relay with a second set of contacts 41, 42 and automatically varying the tension on springs 43 mounted below each of the arms 23, 2*, -18 proportional to the load on the feeder. and 25 respectively. These contacts are For holding the member 47 in position when mounted at such a distance below the arms no load is upon the circuit, 1 provide stops 23, 21 and 25 respectively, thatwhen any 53 cooperating with each arm of member 47. 8o arm moves to close its upper contact that, Let us assume for instance that the load under ordinary conditions, the other arms on the feeder is 100 KW and the wattmeter :of the relay will not engage their lower conselective. relay is operative on an unbalanctacts. This is accomplished by the fact that ing of 1 KW, that is, on one per cent. un-

the lower contacts cannot-be engaged by: balancingi-between phases. It now the load, 5

their respective arms unless the pull moving for some reason, increases to 1000 KIV, by the third arm upwardly. is sufliclent to overthe operation f my spring adjusting means, come the tension exerted by the spring conthe relay is no longer-operativ on an unl 26,27 and 28. l Connected with each" balancing of 1 KW which would, be one.-

" of the contacts 41, -12'and 43 are phase 112- tenth per cent. unbalancing but due to the 0 cording or indicatmg devices514,145 and -16, solenoid windings 50, 51, 52, the member 47 respectively, which are similar in all respects is raised to assume a position proportional to phase recorders 31, 32'and.33., Phase reto the increased load and a proportionally corders 4A, 45 and -46 are'connectcdl to tlie r increased tension thereby exertedupofi'the contluctors 34, and 36, respectively, so springs 18 so that to cause an operation of 5 tha t-hecontacts 41, 42 and 43 andphasethe relay, a greater tension of the springs recorders 4st, and 46, respe tiv'elyyare iu' must be overcome. Therefore due to the shunt relation tothe cont ts 6, 27, and 28 position of member 47, the tension: on and phase recorders '31, Z an'd 33 respcc-' springs 48 is such thatit requires an unbal 35 tively. Irrespective, therefore, of whether ancing of IO'KIV before the relay will opme one of contacts 26, 27 or 28 on one of contacts 41, or 43 are engaged by'their .re-' spective arms of members 22,'the alarm device 37 and relay 38 are energized and by an 40 examination of the phase recorders, the contact engaged canbe detern'iined. In order. that my wattmeteri relay may respond to the same percentageof load unbalancing between the phases independent crate or as before an unbalancing of 1%. Thus I have provided means for maintaining the relay responsive to a fixed and .definite percentage of unbalancing of the load conditions,' irrespective of the actual value of the load 'on the feeder. 7 I

There are so many different conditions which may 'ex' t upon a transmission line when a line wire breaks, that it is practi-l 45 of the actual value of the load. I provide my cally impossible to provide one relay device 11 relay with meansf for automatically maintaining the sensitivity of the relay constant under varying conditions of load so that the relay is always msponsive tow the same perto suitably respond to every possible condition. My wfattmeter selective relay will -protect thcline from practically all conditions of broken line wires but to meet everyemer- 5 centage of unbalanmngirrespetive of what gency that may arise, I use, in some in- 0 actual value of thelload may be. "This stances, in combination with this relay; anmeans com rises an additional three armed other relay. To fully protect a single feeder member 4 movably positioned above the ofa grounded neutral system, I use as shown armature 22, the arms of which cooperate in Fig. 5, in combination with my wattmeter 55 With and a1'e ,resiliently connect (1 to the selective relay at station A, which is responarms 23, 24 and 25-respectively, y adjustsive to unbalancingof the power or load Oblespring'members 48 thereby p 'oviding a conditions on the feeder. a second relay spring adjusting means fofmain aining the which is responsive to unbalancing between 01111923, 24 and 25 of member 22 ih-1nechanithe feeder and ground. It is understood as is? cal balance. Secured to the member 47 is a shown in Fig; 1 that a duplicate phase selecrod 49 which with member l7 serves as an armature or core of a solenoid-totaled by the windings 50, 51; and 52 connected in series with the secondaries of current transformers 65 16, 1 and 18 respectively-and current coils tive relay; is connected at station B wliich I have on'iitted showing in F ig. 5 for reasons of clearness' This ground responsive relay 54: receives current from the secondary of a transformer 55 conn cted between the'ncu -but upon the occurrence of a break in any line wire causing a current to flow to ground,

the relay 54 is energized and closes its contacts, which are in parallel to the contacts of the relay or solenoid 38, to'complete the circuit oftrip coil 39 for-the oil switch 40 and thereby disconnect the feeder, the tripp ng coil 39 being arranged so that its circuit is completed inresponse to either the phase selective relay or the ground responsive relay. I j

In the connection betweenthe neutral of the system and ground, I provide a disconnecting switch 57 which is adapted to engage eithei-contacts 58 or 5910 connector disconnect respectively the transformer 55' and hence render relay 54'operative or'in feeder connected to .a

operative. In like manner I provide a 'duplicate relay connected in the neutral ofthe system at station B which may berendered operative or not as desired;- With a single shown in-Fig. 5, the switch 57 is moved to engage contact 58 thereby rendering-the reday 54 .operative' but whenseveral' feeders are 1 connected to-the power station', -relay" 54 is.

not selective but is-like'ly to open the circuits of all the feeders when-a. break occurs on anyone and hence in such instances I move switch- 57 to engage contact 59 and thereby hold the relay '54 1noperative.

When as 'stem of distribution comprises a plurality o feeders, such as is. shown m Fig.

l 4 in which a single line diagram-is shown 40 for each feeder, I' use my phase selective re-- lay on each end of each'feeder, a, b, c which under practically all conditions of broken line will operate-to select the feeder upon which a broken line wire occurs as only the relay on the faulty feeder will be operated,

- and will also select the phase of the feeder at fault as: already described. To protect I f 'againstcthese few conditions for whichfiiy nnd=-responsive -rel ay;is applicable I use in combination with -my phase selective re lay, for a plurality of radial feeders, the re; lay scheme .which is covered in the U, S.

Patent 1,203,556 granted to Archibald II. Davis or for a plurality of arallel feeders,

the relay scheme covered in t e U. 8. Patent ,53 granted to Archibald 'H. Davis's-i If such a condition eiists that a break in a line wire causes both ends of the! wire'to. touch the ground, when the load is light on the other two phases, my phase selective rellayhas difiiculty in selecting such a fault.

g e high resistance to ground will, however, allow current to flow back through the neutral, and if there were but .60-cycle currents in the neutral, the detection of one of these principles of resonance! magnify power station, as

' systems,

magnets and connections, for

oneagtharm.

extremely small currents due to the high resistance ground would beeasy but there exists on nearly all systems harmonics which cause a current through the neutral to ground. In order, therefore, to make relay 54 sensitive, it must be selective for the 60 cycle current. This I accomplish by introducing into the relay circuit, a device 60 having a condenser action shunted by a spark gap 61 for purposes of safety. The condenser 60 has a variable capacitance which is so chosen relative ,to the inductance of the winding of relay 54 that a neutral frequency is given to this circuit corres onding to the generator frequency, by wel -known y other frequency will find greatdifiicult 'in getting through the inductance offered y the wind-' ing of relay 5 4. Naturally the-ratio of inductanceto}. acitance ivqfl'm'ld be. chosen to case man y 1 r. 1 In Figs. 5 and' fi'I have shown'my'phase selective watt'meter relay with connections for .phase '1" only, :it being understood that similar 'connections,ja s shown. inFigl3, exist from the other two 'phases', these connections being omitted for reasons-ofclearness. For

the same-reason I have omittedthe showing of my spying adjustinfg For protectingafeeder a on-grounded neutral system for a few conditions --for which my phase selective may not be selective, I'use in combination with my phase selective wattmet errelay, as with grounded a ground responsive relay but this relay is of d-ifi'erentconstruction than the relay used to respond to the same. conditions on grounded s This relay is of a'construction similar to that shown and de scribed in my application for Letters Patent, Ser. No. 492,846, and popularly known as y arcing ground suppressor relay. This rel y, as shown in Fig. 6, comprises an armature or three aimed member 62 pivotally sup-' ported at its center and carrying a. contact lrod 63 depending therefrom. Each arm of the member 62 carries movably-supported thereon by. knife ed ebars which carry the mov le members or armatures of two electromagnets 65 connected in'series -and receiving current from the secondaries of potential transformers 66 connected between .each phase amdground. Each arm of the relay is, therefo v sive to the tential'between each p and ground. or reasons of clearness, I have shown the relay: provided with-the electm: one phase only it understood that similar connections are made for the other two phases. The ground responsive relay is held in mechanical balance by adjustable springs 67 Normally the pulls exerted on rn'eans'for the relay,

respon- I each arm are equal but when a break in a contact 69, 7 Cor 71, movable contact 72 car- .ditions existin line wire occurs of a characterto cause an unbalancing between the feeder and ground, a greatly reduced pull is exerted on the arm correspondi to the faulty phase or broken line wire W-lllOll'IGSllltS in the pulls exerted on the other two arms of member 62 overcomingit lt' ll of the arm corresponding to the fault'g gase. The member 62 is thus actuated to cause the contact rod' 63 to more into a position to close acircuit from the battery 68 through'the corresponding fixed ried by the rod 7 63, through the rod and thence through the auxiliary relay 0r solenoid 73 back to the. battery 68. This solenoid 73-gcloses its contactsw hich are in parallcl with. the'contacts closed -by the solenoid 38 to close the circuit of thetrip coil and openthe oil switch 40, vboth the phase selective and ground responsive relays '0 crating a common tripping circuit for the oi switch. v3 7 As there are nearly-a hundred conditions which may exist on a feeder when a line wire breaks depending on the character of vthe system andthe nature oithefbreakasheretofore outlined, a. description of theoper ation' of'my-protechive means pro tect a feeder under cach 'condi-tioli would be prohibitive. In order? however, to more clearly bring outmy scheme of protection, I will" briefly describethe dperatioxi-Eof niy protective means underai few of-the inany' con- 'g -s' upo1r "-the oc urrence? '0 broken line Wires. I

Let us take" first the protecti ndf a f e eder 5 p v at 7'5 occurrcd such that the resistance to on a grounded neutral syste zTo ineet;

every condition of broken li e ftlMtmajr occur on such a feeder, I use, n1 phase selecthe wattmeterflo'r' load responsive relaconnected at both endsof the 'ler-iin (one 'bination-with my-.-ground' res "nsive relay 54 rcsponSiVe'tQ unbalancing .betweeath' fccdcr and ground.- As 13m example of character of break wlnichniay occur, we will assume one in which neitherend'ot-the' line wire touches ground, :as shown at 74on phase 3. causing thereby an open circuit in vphase 3.! As conditions vary according to tl1e' ]')ositiohof the break on the feeder, we will assunie such a. break occurs near the powerstatidfi A. As this character of break causesno apprcciaible unlralancing between the, feeder and ground, relay fitwill inoperative. An open circuit on phase'3pliowevcr cap" sthe current iljthis phase-to fall pmetic ail y to zero. This reductionof current in phase 3 causes, for the rea'sxms previq riisly stated, a zero pull on arm of my selective relayby wattu'ietcr element 6 (mr rcspon ing to this phase. The pulls oxcrt 'uhou "arms 23 and 24 by]wattineter-'cleinents' 4 and 5 respect-Holy, (:o rrespondmg to phases 1 and 2 rcspectivel v att. to raise arm'25 and move it into engagement wit-hits c'ontactZS to close regarded.

. notifies the operator oi the operation oi the relay and phase recorder 33 indicates phase 75 3 at. fault and 2lllXlli;lI relay 38 closes the tripplng circuit through trip coil 31,) to open.

the oiLswit'ch 40. In like manner my phase selective relay at station. B simultaneously perates to' indicate phase 3 at fault and 0 open its oil switch due to a zero pull by wattmcteir element 9.

Suppose a break occurs in which only the vbroken line wire nearest station A. touches theg ound, as shown at 75 on phase If-g5 the ground is of low resistance it. will be evident that'the potential on phase 2 falls practically to. zero with a consequent opera tlon, for the reasons stated, of wattmetcr element 5 to open the feeder and indicate the faulty phase. The wattmeterrelay at stat on also operates to select phase 2 at faultand open the feeder, due to'the fallof currentionphase 2 to zero causing a zero pull wattmctcr elcmcntS. .As'this char operates to open the oil switch due to the current to ground from phase 2 returning over the grounded neutral connection. p Suppose this character of break as showngrou'nd "was'such. that. a great rush of current occurred-to ground with little fall in. potential e. the current increases more than the voltage decreases. Upon such 5a 4 condition, thepull exerted by the wattineter element 5 would'be strong enough to overpower wattmcters 3 and 4 and pull the arm 24 of the relay down, engaging contact 42 and operating the alarm 37 and auxiliar Y rel'ay'38 as before, but actuating phase re. c'order $13 to indicate phase2 at fault. Arms 23 and 25 will close their upper contacts 26' and 28, respectively, thereby giving a .false '115 indication on their phase recoiders3l and 33 but it is understood that when. one of the phase recorders 44, 45 or 46 give an indication of afaulty phase, that.- the operation of phase recorders 31 and 32 or 33 must-be dis:

If this condition (if-break was such that a ground occurred havino" a resistance of a value such, that the ibli'tl' or power on phase 2 is equal to that of the normal power or load of the othcr'two phases, 125. then lll phase select-irerelay.would not be operative but this condition would be taken care of by the operation of relay 54.

ll wc assume-a break occurs in which only i the line wire nearest station B touches the ground through a low or inedium'resistance, as shown at 26 on phase land that the break occurs this time nearer-the station 13 than station A, then due to the charging current on phase 1, which is 90. in advance of the electromotive force, a condition of zero power factor exists on phase I causing, for the reasons stated, a zero{ pull' by wattmeter element 4 with the corresponding operation of the wattmeter relay to open the oil switch 40 and indicate phase Las at fault. The re lay at station B operates to open its switch and select hasel at fault due to the fall of potential on phase lto zero giving a zero. 15 pull by wattxneter element 7. I

Let us consider now a condition of break on a feeder of a non-grounded neutral sys-" tem. On non-grounded systems, I use as shown in Fig. 6-a different construction of ground responsive relay in combination with my phase selective rela Assume a break oecurs'of the character 5 Own at 77 on phase 3, causing both ends ofthe li'ne wire to touch the ground. Wattmeter element 6 of my relay at station A and wattmeter element 9 of the relay at station B have a zero pull due to the drop in potential on phase 3 to the operation of both relays to zero causin selectively indicate .phase' 3' at fault and,

open the oils'witches at both stations. My

cooperating groundres onsive relay alsooperates underpthis condltion of break dueto the fact that the potential of phase 3 to ground falls to'zero. It is believed from the oregoing descri tion that the operation of my protective re ays on all other conditions of broken line wire will be apparent without further descrip'tion.-

My invention may be embodied in other 40 forms than that shown and'described and I,

therefore, do not wish to be restricted to the precise. construction shown, but intend to I cover in the appended claims all changes and modifications which are within the scope of my invention and will be apparent to those skilled in the art.

What I claim as new and desire to secure by Letters Patent of the United States is 1. In a system of distribution, the combination with a feeder, of means for protectino said feeder upon the occurrence thereon o conditions occasioned by a broken line wire including a relay'device differentially operated in, response to the product of current,'-, a 65 potential and power factor existing on each phase of the feeder when a line wire breaks to selectively indicate the-phase of the feeder at fault. I 1

2. In a system of distribution, the combination with a feeder thereof, of means-for protecting said-feeder under abnormal conditions occasioned by the occurrence of a broken line wire, including means responsive to the product of current, potential and .power' factorin each phase of said feeder,

and means differentially operated "in 'response to an unbalancing, of said first mentioned means to selectively indicatethe phase causing such unbalancing.

3. In a system of distribntion,the combination witha feeder thereof, of a phase se lective relay differentially operated in 're-' sponse to the product of current, potential and power factoron each phase of said feeder occasioned by a "broken line wire to indicate the phase at fault, anda switch operative in response to the a'ctuationof said relay to open the circuit of said feeder.

1-. In a system of distribution, the combi- A nation with a feeder-,1 of means for 'protecting said feeder upon the occurrence thereon of a broken line wire comprising a relay device differentially operated in response to the product of current, potential and power. factor on each phase of said feeder to selectively indicate thephase of said feeder at fault, another relay operative in response to an unbalancing between each phase of said feeder'and ground, and a switch operative in response to either of said'relays to open the circuit of said feeder.

5. In a system of-distribution, the combination with a feeder, a differentially operated wattmeter element relay operative in response to a load unbalan'cing on said feeder due to conditions of a broken line wire'to selectively indicate the phase of said feeder upon which such brokenline wire 00 "curs, and a switch operative in responseto the actuation of said relay to open the cir' -cuit of said feeder.

6. In a system of distribution, the combination with a feeder,of means for protectin said feeder upon theoccurrence thereon 0 conditions occasioned by a broken line wire including elements responsive to the product of current, potential andpower factor of each phase of said feeder, means differentially operated by said elements, and recording means actuated in response to the actuation of said first mentioned means to indicate the phase at fault.

7 In a system of distribution, the combination with a' feeder thereof, of means for disconnecting said feeder from said system upon the occurrence thereon of all abnormal conditions occasioned by a broken linewire thereon and indicatingv the phase of said feeder at fault, includin elements connected to each phase'of said eeder responsive to 12.0 the product ofeur'rent, potential and power factor, means interconnecting said elements and differentially operated thereby, recording means selectively operated in response to the differential operation of said first mentioned means to indicate the phase at fault, and a switch connected to said feeder and opened in response to said first mentioned means.

8. In a system of distribution, the combirent. potential-and power factor of. eachnation with a feeder thereof, of means for ln'otcct-ing said feeder upon the occurrence thereon of a broken line wire, includin single phase wattmeter elements connectc to the-phases of said feeder. a contact making member differentially operated in response to said wattnietcr elements. circuits selectively closed in repsonse to the move-. ment of said member into-switch closing position, means actuated in response to the selective closing of said circuits to indicatethe phase atv fault, and a switch controlled by said member to open the circuit of said feeder. y

9. The method of protecting a feeder of a. system of distribution upon the. occurrence thereon of abnormal CO]](lltl0IlS. occasioned by a broken line wire which consists in caus- -'ing the unbalancing of the product of curpliase due lto albroken line wire to operate a device and maintain an indication of the phase at fault and then causing the opening oftlie circuit of the faulty feeder.

10.,In combination with a transmission line, a phase selective rela'y responsive to all abnormal renditions on said line due. to'a broken line 'yvi're'inc'luding an element cotresponding to each phase, each of said ele- 3C iiients being operated in response to the prodber,.fspr1ngs connecting said members and adjustable to hold said first mentioned memtion, said member having a contact engag net of potential,- current and power factor, a inember in common to sa d elements -opera tire thereby with n differential aetion,":'ui'd phase record] "devices corresponding to 35 H2ll(l elements se. eil-tively actuated-in response to the actuatioiilof said relay to indicate the phase at fault-.-

. 11. In combination with a transmission lii'ie, a phase selective i'elay- 'respoiisive to I 40 abnormal conditions on said line occasioned by a broken line wire, comprising a Wvattmeter element" responsive to conditions on each phase, a member differentially movable by said elements into contact. engaging-posiing position corresponding to leach wattmeter element, means for indicating the eon tact engaging position into which said member'is moved, and an indicating device op- 50 erative i'n responseito the movement ofsaid member into any of contact engaging positions.

12. In. combination with 'a transmission line, a relay responsive to a predetermined percentage of load unbalancing on said line,

and means for maintaining said relay re-- sponsive to the same predetermined percentage of load unbalancing independent of the actual value of load on the line.

13. In combination with a transmission line, a phase selective relay responsive to abnormal conditions occasioned by a broken line wire including: load responsive elements connected to each phase, means interconnecting said elements to cause said relay to opcrate differentially in response to a predetermined percentage of load unbalancing 1n said feeder, and means operatively relatedto said first mentioned means for maintaining said first mentioned means responsive to y the same percentage of load unbalancing inmal pos'itionas long as the pulls exerted on ill(l nieiiiberby said elements are equal but movable differentially in response-to an unequal pull by said elements. and means o'peratively related to said member and responsive to the load on said feeder to cause a greater differential pull as tlie'load on said f oder; creased to operate said member. In ombination with a transmission line, 0 a's'e selective relay responsive to abn'orni'al "conditions occasioned by a broken line. wire including wattmeter elements coniiected-to each phase, a member operatively related tosaid elements and differentially operated 'there-by, a second movable member cooperating with said first mentioned memlierfi-i'i'f'mechanical balance, and electroresponsive means responsive to the load .on said feeder for positioning said second memher and exerting a tension on said springs proportional to the load on the feeder.

16.*In combination with a transmission line, a phaseselective relay responsive to load unbalacingon said feeder comprising 'loa'd responsive elements connected to each phasmmeans for holding said elements normally balanced against each other, and means normally positioned in response to the load on said line and cooperating with constant irrespective of the actual value of load on. the. feeder.

17. In a system of distribution having a. plurality of feeders, of means for protecting said systen'i fromthe occurrence thereon of a broken line wire including elements responsive to thevproduct of current, potential and power factor in each phase of each feeder, means differentially operated bysaid elements in each feeder to select and indicate the phase of the feeder at fault and means for indicating that feeder of the system having the broken line Wire thereon.

IS. A relay includinga plurality of watt meter elements. a member operatively related to each of said elements and held normally'balanced when the pull exerted by said elements are equal but differentially no said first mentioned means to maintain the sensitivity of the relay to load unbalancing movable in response to an ui'ibalancing between the pulls exerted by said elements,

. to assume a position corresponding to that element having the weakestpullQ 19. A relay including a plurality of single phase wattmeter'elements, a member operatively related toeach of saidelements and held normallflbalanced when the pull exerted by said e ements are equal but differentially movable in response. to an unbalancing between the pulls exerted by said elements to assume a, position corresponding to that element having the weakest pull, and. means for varying the amountof unbalancin -necessary to operate saidmember.

0. A rela comprising threesingle phase wattmeter e ements having movable and fixed coils, a-threeearmed member carrying on each arm the movable coils ofsaid wattmeter'ele'ments, said member being movv spouse to the engagement of said contacts.

r 21. In combination with a transmission line having its neutral polnt grounded, ofa

relay responsive to currentin said neutral connection, and means cooperating with sa d.

relay for renderingit operative only oncurrents of generator frequency.

' a 22. In combination with a grounded non-'- tral connection of a system of distribution,

a relay responsive to current fiow through said grounded connection, means having .a condenser action operatively related to the conditionof resonance insaid relay circuit corresponding to each element, contacts engaged by each arm in'response to a certain differential movement of said member under one condition, and independent cOntaCtsengaged by each arm in response to a predetermined movement of said member under another condition, and means operatively related to each contact. to indicate its engagement.

24. In combination with a transmission line, a phase selective relay responsive to abnormal conditions upon said line occasioned by a broken line wire, including a \vattmeter element responsive to conditions on each phase, a member differentially movable by said elements into contact engaging positions, contacts corresponding to said Wattmeter elements located on one side of'said member and adapted to lie-engaged by said member, a second set of contacts corresponding to said wattmeter elements located on the opposite side ofsaidmember and adapted to be engaged by said member, and means for indicating the engagement of either of said first mentioned or second set of contacts by said member.

In witness whereof I have hereunto set my hand this 6th day of April, 1916. inductive winding of said'relay to produce ELMER E. F. CREIGHTON. 

